Diaphragm pump of minimum displacement loss



Oct. 6, 1964 p, F, Hoon ETAL 3,151,568

^ DIAPHRAGM PUMP 0F MINIMUM DISPLACEMENT LOSS Filed July 26, 1961 INV EN TORS WZJ United States Patent Oli 3,ll,568 Patented Oct. 6, 1964 ice 3,151,568 DiAPHRAGlVI PUMP GF MENIMUM DEPLACE- MENT LGSS Paul F. Hood, Clarkston, and Gerald W. McArthur, Flint, Mich., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed July 26, 1961, Ser. No. 127,664 2 Claims. (Cl. lr03-159) This invention relates to pumps and more particularly to diaphragm pumps for handling uids such as liquids and air or gases customarily needed in the operation or internal combustion engines.

In diaphragm pumps as heretofore employed, a loss of eiiiciency has been apparent as the pumping diaphragms would unduly yield on suction and pressure strokes losing considerable pumping displacement. lt has been found that, in accordance with the present invention, a more full or potential displacement may be retained by suitably supporting the diaphragm while simultaneously providing or the requisite exing of the diaphragm material.

An object of the present invention is to provide an improved pump capable oi retaining maximum potential displacement for attaining pumping eiijciency.

A feature of the invention comprises a diaphragm pump utilizing a diaphragm material having iieXed or pliant portions separated by a rigid toroidal rim and a clearance space.

These and other important features of the invention will now be described in detail in the specification and then pointed out more particularly in the appended claims.

ln the drawings:

FIGURE l shows an elevation view, partly in section, of a combination fuel and vacuum pump as one embodiment of the present invention; and

FIGURE 2 is a sectional view looking in the direction of the arrows 2-2 in FIGURE l, an upper diaphragm reinforcement plate being omitted.

The combination pump as herein disclosed, in overall aspects, is much like that disclosed in the United States Patent No. 2,189,526, granted February 6, 1949, in the name of A. M. Babitch, and entitled Double Acting Vacuum Pump. It will become obvious, however, that the invention may be applied to single action pumps,

A complete description regarding the pump, extraneous to the diaphragm, is not set forth herein as the present invention obviously could be used on a liquid as well as on a vacuum or air pump and only the diaphragm structure need be considered fully to understand the invention.

in FIGURE l, the supporting body or" a combination vacuum and fuel pump is shown at l0. Beneath this body is suspended a conventional fuel pump 12 and above it is located the upper portions of a vacuum booster pump 14 of the double acting type. The casing of the vacuum pump includes a one-way valve 16 leading from a displacement or pumping chamber 42, a one-way valve 243 leading from a wiper motor to a displacement or pumping chamber 22 and a Valve 2li adapted to lead through a conduit 2.6 to an engine intake manifold. A coil spring 23 acts downwardly upon a diaphragm generally indicated at 343 and a plunger 32 is slidably mounted in a seal bearing 34 and adapted to be reciprocated by lever means 35 pivoted at 37. The plunger 32 extends through the diaphragm 3) and bears opposed shoulders 3S and 4t) for clamping parts of the diaphragm together. The diaphragm 3? separates the displacement chambers 22 and 42 and both pumps 12 and 14 are adapted to be reciprocated by engine cam shaft action as is well understood in the art.

The diaphragm Si) includes exible pliant material constituting two sheets dd and 46. The peripheries of these sheets are held together and in sealed relation between the registering walls 4S and Si) of the vacuum pump casing. These walls are held in position by bolts 51. It will be noted from FGURE 2 that the invention is not limited to a circular diaphragm arrangement and with the pump illustrated an elliptical construction has been adopted. ln FIGURE 2, the casing is shown as having a passage 52. This passage connects With an opening 54 shown in FIGURE l so that the two displacement chambers 22 and 42 are connected by Way of the valve 20 as will be understood. This is not a novel feature but is somewhat like that in the patent above referred to.

The diaphragm Si? not only includes the pliant material of the sheets 44 and but also two opposed reinforcement plates 56 and 5S as Well as a dat intermediate member 69. The latter is sandwiched or interposed between the sheets 4d and 56 and held, with the latter, tightly within the reinforcement plates 56 and 58 by means of two rivets 62 as Well as the shoulders 38 and 4@ of the plunger 32. The dat member o0 has a rigid rim 64 in the form of a toroid enclosed in the pliant sheet material or the diaphragm. This rim has a circular cross section and cooperates with the sheets 44 and 415 in deiining a closed space 66. This space is so located between the registering walls of the casing and the rim and so proportioned that the diaphragm 3d may reciprocate through the plane of the clamped periphery of the pliant sheets.

The flat intermediate member o@ and its rim 64 may be made of a light metal such as aluminum or magnesium. This is also true with respect to the reinforcement plates S6 and 58. Lightness for these parts is, of course, advantageous to minimize the inertia forces present in the operation or" a diaphragm pump. The upper and lower portions oi the displacement chambers 22 and 42 are of such configuration as to provide minimum clearance as the diaphragm Btl reaches the corresponding ends oi its range of movement. L1 assembling the pump structure, the diaphragm assembly 30 is located in the casing with the aid of the bolts Si without distorting the pliant material by stretching. In other Words, each sheet 44 and 46 is preformed in a mold so that when the pump is assembled the requisite space 66 is achieved and no straining or stretching of the pliant material is incurred. The space 66 adjacent the rim 64 is made adequate to permit dexure ot the pliant material in accord with the requisite travel of the diaphragm. The space 65 is neither vented to atmosphere nor vacuuriized. lt is at atmospheric pressure or is slightly pressurized depending upon the temperature conditions encountered by the pump. The diaphragm construction is such that it minimizes the loss of potential pump displacement available. This minimization is due to the opposed convex surfaces of the rigid rim 64 forming a definite and positive backing for the pliant material of the sheets 44 and 46 at the moments when maximum displacement is determined.

We claim:

l. A double acting diaphragm pump including a casing having inner wall surfaces, a diaphragm cooperating with said surfaces in dening displacement chambers, the said diaphragm comprising pliant sheet material, clamping plate means and a dat member, said clamping plate means and dat member being rigid and retained in close Contact with a central area oi said diaphragm and by which the atter is adapted to be ilexed, said dat member having a rigid rim with opposed convex surfaces and in the form of a toroid enclosed by said sheet material outside said ra Y Y central area interposed between said inner wall surfaces material marginal portions at aY corresponding end of the and said clamping plate means and cooperating to give Y pumpstrolie. Y a definite and positive backing for said sheet material at least at one end of the pump stroke, References Cited in the tile of thls patent.

j 2. A dOllbie aCtng diaphragm pump aS Set forth in 5 UNITED STATES PATENTS claim 1, marginal portions or" said pliant sheet material Y extending outwardly Vfrom said rigid rirn, the said rigid lltllll Dlb'g 3 np' U y y 1 run and sald marginal portions cleaningJ a closed space ex 2,931,311 Ulm etraL Apr* 5 1960 tending alonglthe perimeter of said rim and said rim being adapted to supply a firm backing for one of said sheet 10 3,070,029 Russell Dec.' 25, 1962 

1. A DOUBLE ACTING DIAPHRAGM PUMP INCLUDING A CASING HAVING INNER WALL SURFACES, A DIAPHRAGM COOPERATING WITH SAID SURFACES IN DEFINING DISPLACEMENT CHAMBERS, THE SAID DIAPHRAGM COMPRISING PLIANT SHEET MATERIAL, CLAMPING PLATE MEANS AND A FLAT MEMBER, SAID CLAMPING PLATE MEANS AND FLAT MEMBER BEING RIGID AND RETAINED IN CLOSE CONTACT WITH A CENTRAL AREA OF SAID DIAPHRAGM AND BY WHICH THE LATTER IS ADAPTED TO BE FLEXED, SAID FLAT MEMBER HAVING A RIGID RIM WITH OPPOSED CONVEX SURFACES AND IN THE FORM OF A TOROID ENCLOSED BY SAID SHEET MATERIAL OUTSIDE SAID CENTRAL AREA INTERPOSED BETWEEN SAID INNER WALL SURFACES AND SAID CLAMPING PLATE MEANS AND COOPERATING TO GIVE 